Arthroscopic-Assisted Treatment of Distal Radius Fractures

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CHAPTER 20 Arthroscopic-Assisted Treatment of Distal Radius Fractures

Sidney M. Jacoby, MD, Osterman A. Lee, MD

The advent of wrist arthroscopy in the early 1990s marked the beginning of a novel and valuable adjunct in the treatment of distal radius fractures.¹ Anatomical reduction, stable internal fixation, and preservation of soft tissues are cornerstone concepts in fracture reconstruction. Distal radius fractures represent a unique subset of upper extremity injuries because they often involve not only articular margins but also surrounding soft tissue structures critical to normal wrist function. As arthroscopic technology has evolved at a rapid pace, so, too, has the utility of wrist arthroscopy in the treatment of various subtypes of distal radius fractures.

Arthroscopic-assisted reduction/internal fixation (ARIF) provides a unique, magnified and illuminated view of the distal radial joint surface that allows precise reduction of fracture fragments. Comminuted fractures involving the distal articular surface are particularly difficult to manage because they have an inherent tendency toward instability, either by shortening or collapse, and are less amenable to closed manipulation and casting. Arthroscopy allows the surgeon to explore the biconcave distal radius articular surface and remove chondral defects, loose bodies, and fracture fragments in both the radiocarpal and distal radioulnar joints. In addition to assisting with percutaneous pinning, external fixation, or limited open reduction techniques, arthroscopic visualization and repair of associated intercarpal soft tissue injuries is a crucial component to improving outcomes.

Precise reduction of the distal radial articular surface is critical in preventing the late sequelae of post-traumatic arthrosis. Numerous studies have shown that a poor result is likely if more than 1 mm of articular incongruity is present at the radiocarpal joint (Figs. 20-1 to 20-3).²^–⁶ Subchondral hematomas in the radiocarpal joint have also been shown to cause the early onset of mild osteoarthritis and worse outcomes after 1 year, even without a fracture line as demonstrated by arthroscopy.⁷ Arthroscopic irrigation and débridement of hematoma may therefore ultimately improve outcome by removing a possible impetus for early post-traumatic degenerative changes.

FIGURE 20-1 Anteroposterior (A) and oblique (B) radiographs of a distal radius fracture with more than a 2-mm articular incongruity results in traumatic arthritis.

FIGURE 20-2 Radiograph of distal radius fracture with more than 2-mm radial ulnar diastasis.

FIGURE 20-3 Radiograph of distal radius fracture with more than 2-mm dorsal volar diastasis.

ARIF affords a well-lit, magnified view of the distal radial joint surface with minimal morbidity. It has been shown to be superior to C-arm and plain radiographs for assessing both displacement between articular fragments as well as the diagnosis of soft tissue lesions.^8,⁹ In a study performed by Edwards and coworkers of intra-articular distal radial fractures that underwent closed manipulation and percutaneous pinning followed by sequential assessment of reduction by C-arm, radiography, and wrist arthroscopy, 33% of cases judged to have had optimal reduction by C-arm and radiography were found to have an articular displacement of more than 1 mm by adjunctive arthroscopy.⁸ It has also been shown that arthroscopic-assisted reduction and external fixation of distal radius fractures permits a more thorough inspection of the ulnar-sided components of the injury when compared with fluoroscopic-assisted reduction and external fixation of distal radius fractures alone. In addition, a prospective cohort study showed that at follow-up examination, patients who underwent arthroscopic-assisted procedures had a greater degree of supination, flexion, and extension than patients undergoing fluoroscopic-assisted surgery.¹⁰ It is now recognized that intraoperative fluoroscopic imaging does not provide sufficient precision to visualize a 1-mm step-off in the radial articular surface despite often satisfactory postoperative radiographs.^1,¹¹

Indications and Contraindications

Although the main indication for ARIF of a distal radius fracture is an intra-articular step-off of more than 1 mm, arthroscopy is particularly useful in the management of unstable or displaced intra-articular fractures as well as comminuted articular fractures. Additional fracture patterns amenable to ARIF include radial styloid fractures, lunate die-punch fractures, three-part T fractures, and Melone four-part fractures.¹² Other reasons to perform arthroscopy may include radiographic signs of concomitant injury, including diastasis of intercarpal joint spaces, subluxation of the distal radioulnar joint (DRUJ), or a broken carpal arch. ARIF may be contraindicated in the setting of forearm compartment syndrome, untreated median nerve compression, severe soft tissue injury, open joint injuries, unreduced carpal dislocations, infection, and complex regional pain syndrome.¹³

Timing of Surgery, Setup, and Portals

ARIF can be performed under either axillary block or general anesthesia between 3 and 7 days after the index traumatic event. Waiting a few days allows the surgeon to avoid difficulty with visualization secondary to active bleeding. Conversely, if arthroscopy is performed after 7 days, the fracture begins to consolidate and manipulation of the fragments is more challenging.

Before introducing the arthroscope, a pneumatic tourniquet (set at 250 mm Hg) is applied to the upper arm and an Esmarch bandage is wrapped around the forearm to diminish fluid extravasation into the muscle compartments. Lactated Ringer’s solution is used for irrigation because of its rapid absorbability.¹⁴

The operating room setup and arthroscopic portals are virtually identical to those used in an elective wrist arthroscopy. Either a horizontal or a vertical arthroscopic setup may be used (Fig. 20-4).¹⁵ Swelling often makes it difficult to palpate the extensor intervals, so the use of bony landmarks including the bases of the second and third metacarpals, Lister’s tubercle, radial styloid, and distal ulna is useful. Traction provides ligamentotaxis, which aids in fracture fragment reduction. A useful technique to avoid iatrogenic cartilage damage during the introduction of arthroscopic instrumentation is the use of a 20-gauge needle in the proposed 3-4 portal before making a skin incision.¹⁴ If the needle passes unobstructed without engaging bone, the portal is likely in the correct position. Fluoroscopy can also aid in needle placement and portal establishment.

FIGURE 20-4 Setup for arthroscopic-assisted internal fixation. Note vertical traction tower, arthroscope, and C-arm fluoroscopy.

The arthroscopic sheath is usually introduced in the 3-4 portal, and an outflow cannula is established in the 6-R portal. The first image obtained on entry into the joint is usually that of fibrin clot and debris. Lavage is particularly useful and nearly always necessary to clear the joint and provide unobstructed visualization for precise fragment manipulation and reduction. Washing out fracture hematoma and debris may also contribute to the increased range of motion and functional outcome associated with ARIF.^16,¹⁷

Midcarpal arthroscopy offers significant information to the arthroscopic examination, particularly in the setting of soft tissue injuries suspected with distal radius fractures. Hofmeister and associates showed that a pathological process leading to additional surgical intervention was found on midcarpal examination in more than 60% of patients undergoing arthroscopy for evaluation of soft tissue injuries in the setting of distal radius fractures.¹⁸

Surgical Technique

Distal radius fracture fragments are sometimes reduced with longitudinal traction and external manipulation alone. However, depressed and displaced fragments often require mobilization with either a probe in the joint or instruments such as a Freer elevator placed through a separate skin incision over the fracture. Kirschner wires (K-wires) are also extremely useful because they may be placed in fracture fragments, and, under arthroscopic guidance, depressed fragments may be elevated and realigned via a joystick type maneuver. Once the fracture fragments are appropriately reduced, the surgeon may visualize the articular surfaces with the unparalleled view afforded by the arthroscope.

Two-Part Radial Styloid Fractures

Most radial styloid fractures can also be reduced by closed manipulation. Adequate reduction may be evaluated fluoroscopically, arthroscopically, or by a combination of the two (Figs. 20-5 to 20-8). Because radial styloid fractures have a propensity for rotation, K-wire joysticks can be used to manipulate fracture segments. The K-wires may be inserted through a 14-gauge needle, drill sleeve, or drill tap to protect the surrounding neurovascular structures (radial artery and superficial branch of the radial nerve). Arthroscopic assessment of adequate reduction of the articular surface is best evaluated by placing the scope in the 4-5 portal. Once adequate reduction is obtained, the K-wires may be driven across the fracture or another means of fixation, such as a cannulated screw, may be used for fixation (Fig. 20-9). Arthroscopic assistance is also useful in assessing for associated soft tissue injuries in the setting of radial styloid fractures. Scapholunate tears have been identified in up to 50% of radial styloid fractures, and arthroscopic assistance is therefore useful in assessing for these intercarpal injuries.¹⁵

FIGURE 20-5 Radiograph of two-part radial styloid fracture.

FIGURE 20-6 Arthroscopic view of articular surface of radial styloid fracture.

FIGURE 20-7 Fluoroscopic view of ARIF of radial styloid fracture.

FIGURE 20-8 Follow-up radiograph of patient with radial styloid fracture treated with ARIF.

FIGURE 20-9 A, Arthroscopic view of radial styloid fracture with fracture mobilization. B, Arthroscopic view of radial styloid fracture ensuring reduction with less than 1-mm step-off. C, ARIF of radial styloid fracture with screw fixation.

Three-Part Fractures

The arthroscopic-assisted approach to management of three-part fractures (Figs. 20-10 and 20-11) includes preliminary reduction of the radial styloid as previously described. The reduced styloid segment may then be used as a landmark to reduce the medial fragment (Fig. 20-12). Articular gaps may be reduced with the aid of a bone tenaculum, and depressed articular fragments may be elevated with the aid of a bone awl or a percutaneously placed Steinman pin. In select cases, bone grafting may be required.^19,²⁰ Once again, arthroscopic assistance allows superior assessment of articular surface reduction and assessment of associated soft tissue injuries.²¹

FIGURE 20-10 Schematic drawing of three-part distal radius fracture.

FIGURE 20-11 Three-part intra-articular distal radial fracture.

FIGURE 20-12 Intraoperative fluoroscopy with radial styloid component reduced and pinned and joystick in ulnar column fragment for reduction.

Four-Part Fractures

Melone four-part fractures are characterized by further splitting of the medial segment into volar and dorsal fragments (Fig. 20-13).²² Initial traction allows ligamentous reduction of fracture segments. Attention is first directed toward reduction of the radial styloid, which then serves as a guide for further fragment reduction. A limited open volar incision is usually required to allow adequate mobilization and reduction of the volar fragment. Buttress plate fixation (usually a 2.7-mm condylar plate) allows stabilization of the volar fragment, which may then be used as a fulcrum to reduce the dorsal fragment. Arthroscopic visualization again assists in evaluating adequate reduction of the dorsal fragment.

FIGURE 20-13 Diagram of four-part intra-articular distal radius fracture, with ulnar styloid fracture.

Management of Associated Injuries

Distal radius fractures exhibit a high incidence of associated injuries, including chondral and soft tissue injuries to the DRUJ, scapholunate interosseous ligament, lunotriquetral interosseous ligament, as well as the soft tissue structures on the ulnar side of the wrist, including the triangular fibrocartilage complex (TFCC). Geissler and colleagues reported that as many as 68% of patients with intra-articular fractures of the distal end of the radius had associated soft tissue injuries of the wrist.²³ The most commonly associated injury was a tear of the TFCC (49%), followed by injury to the scapholunate interosseous ligament (32%) and injury to the lunotriquetral interosseous ligament (15%). Twenty percent of patients had multiple soft tissue injuries, and chondral lesions of the carpal bones occurred in 23% to 44% of patients with displaced distal radius fractures. Subsequent studies have demonstrated similar results.^15,^19,²⁴ Arthroscopy, therefore, allows the treating surgeon to promptly identify and treat associated injuries that may otherwise be missed altogether or diagnosed at a later date requiring secondary reconstruction.

Chondral Lesions

Numerous studies have shown that distal radius fractures evaluated arthroscopically revealed cartilage lesions in both the carpus and distal radius articular surfaces in as many as 18% to 44% (average 27%) of patients.^1,^7,^23,²⁵^–²⁷ These lesions include subchondral hematomas, cartilage impaction lesions, as well as chondral fractures. The significance of chondral injury was demonstrated by Lindau, who showed that in one third of patients with dislocated distal radius fractures and chondral defects, early onset of mild osteoarthritis was found in the same area as the identified lesion and worse outcomes were seen at 1-year follow-up.⁷

Scapholunate Injuries

Intercarpal ligaments play a crucial role in the biomechanics of normal wrist function.²⁸ If a complete rupture of the scapholunate or lunotriquetral intercarpal ligaments remains untreated, the resulting chronic alteration in wrist kinematics will lead to a predictable pattern of wrist arthrosis. Early primary treatment clearly yields superior results; therefore, early precise diagnosis is critical.¹³ Arthroscopy allows direct visualization and magnification of the carpus and is currently the preferred imaging modality of many surgeons to evaluate for internal derangement of the wrist.^29,³⁰

In the setting of distal radius fractures, scapholunate interosseus ligament injuries have been reported to occur in 18% to 54% (average 31%) of patients undergoing arthroscopy.^1,^15,^19,^23,²⁵^–²⁷ Geissler and colleagues described a widely accepted arthroscopic classification system of tears of the intracarpal ligaments.²³ Grade I tears represent attenuation/hemorrhage of the ligament with no incongruence of carpal alignment. Grade II tears, as seen from the midcarpal space, represent partial tears of the ligament and add the element of incongruency to grade I. Grade I and II tears have the potential to progress to degenerative wrist disease, but there is no current consensus regarding the optimal treatment, which could include either immobilization or arthroscopic pin fixation for 6 to 8 weeks in an effort to promote ligament healing.

Grade III tears are characterized by incongruence or step-off of carpal alignment when viewed from both the radiocarpal and midcarpal joints. A small arthroscopic probe (1 mm) may be passed through a gap between the carpal bones demonstrating a complete tear of the intracarpal ligament. Grade IV lesions represent gross instability of carpal bones with incongruence and the ability to pass a 2.7-mm arthroscope through the gap between the carpal bones—a “drive-through lesion” (Figs. 20-14 to 20-16).

FIGURE 20-14 Radiograph of three-part distal radius fracture with schapholunate dissociation.

FIGURE 20-15 Arthroscopic view of a grade IV scapholunate tear, a “drive-through lesion.”

FIGURE 20-16 Distal radius fracture with scapholunate dissociation.

In studies that grade scapholunate injuries associated with distal radius fractures, grade II tears are the most commonly reported subtype of scapholunate lesion (roughly 50%). Overall, scapholunate tears are associated with radial styloid and lunate impaction fractures, dorsal displacement of the radius greater than 20 degrees, and static dorsal intercalated segment instability (DISI) on prereduction films. When carpal incongruence is apparent through both radiocarpal and midcarpal portals, and a probe can be passed from the radiocarpal to the midcarpal joint through the scapholunate ligament (grade III tears and greater), ARIF may be indicated. This is best performed by scapholunate ligament débridement and transfixion with K-wires (Fig. 20-17). Grade III and IV tears requiring pinning are reported to occur in 25% to 37% of patients (Figs. 20-18 and 20-19).^19,²³ In some cases, direct arthroscopic repair is not possible and treatment options could include open repair, open repair combined with capsulodesis, or stabilization with tendon transfer.³¹

FIGURE 20-17 Fluoroscopic view after ARIF with cannulated screw in radial styloid fracture and percutaneous K-wire pinning of scapholunate tear.

FIGURE 20-18 Radiograph of radial styloid fracture with suspected grade IV scapholunate injury.

FIGURE 20-19 Radiograph of radial styloid fracture with associated scapholunate tear after ARIF.

Lunotriquetral Injuries

Lunotriquetral ligament injuries are reported in 12% to 15% of patients undergoing arthroscopy in the management of distal radius fractures. These injuries may be associated with a basi-ulnar styloid fracture or volar intercalated segment instability (VISI) pattern on the prereduction radiograph. Geissler and colleagues reported lunotriquetral tears in a series of 9 of 60 patients (15%).²³ Seven of these 9 patients (77%) had grade III complete tears. The other 2 patients had partial tears of the lunotriquetral ligament. In our series, only 5% of patients with identified lunotriquetral tears were considered unstable enough to require pinning with K-wires (Fig. 20-20), but other series report lunotriquetral transfixation in up to 75% of patients with identified lunotriquetral tears in the setting of distal radius fractures.^19,²⁶

FIGURE 20-20 Radiograph of distal radius fracture with associated lunatotriquetral grade III tear treated with ARIF and pinning.

Concurrent Injuries

Roughly 20% of patients may have combined soft tissue injuries in association with arthroscopically evaluated distal radius fractures. Combined injuries most commonly involve TFCC and scapholunate injuries, followed by TFCC and lunotriquetral injuries, and scapholunate and lunotriquetral injuries.^19,²⁶ Slade and coworkers have reported combined fractures of the scaphoid and distal radius treated by percutaneous and arthroscopic techniques.³² They recommend percutaneous reduction of the scaphoid fracture and provisional stabilization with a guidewire placed along its central axis, percutaneous/arthroscopic reduction and rigid fixation of the distal radius fracture to permit early motion, and, lastly, fixation of the scaphoid fracture with implantation of a cannulated headless compression screw. Fractures of the ulnar styloid are frequently associated with distal radius fractures as well. Arthroscopy helps to provide a treatment rationale in approaching management of the ulnar styloid fracture. Loss of the trampoline effect by a probe of the TFCC indicates laxity of the articular disc and may be indicative of DRUJ instability. If there is no demonstrable laxity of the TFCC and a stable DRUJ, the ulnar styloid fracture likely does not need to be stabilized. If, on the other hand, there is laxity of the articular disc and/or DRUJ instability, the ulnar styloid fracture should be fixed with pins or screws.